Revision as of 14:57, 25 November 2013

Welcome to the homepage of Stephen Trumbo. I am interested in the integration of ecological, physiological and evolutionary approaches to animal behavior. Our primary experimental organisms (burying beetles) allow easy manipulation of reproduction, parental care, competition and hormonal state. Student projects at the Waterbury campus are primarily geared to undergraduates, although collaboration with graduate students from other campuses also has been possible. Current research projects can be found below.

Research Projects

Aging

There have been three primary approaches to the study of aging: evolutionary ecology asks why and when we senesce, molecular biology examines the cellular mechanisms of aging, and behavioral ecology addresses how aging affects reproductive effort. We are examining how reproductive effort and performance vary with age, and whether all components of reproduction are similarly altered. Burying beetles provide a useful model because alternative hypotheses for improvements with age (more experience and the loss of less fit individuals from the older cohort) can be controlled easily in the laboratory.

Juvenile hormone

Parent regurgitating to larvae

Juvenile hormone (JH) has numerous physiological and behavioral effects in larval and adult insects. In burying beetles, high levels of JH are correlated with periods of intense parental activity. Manipulation of JH levels, however, seems to have minimal effects on care-giving. In collaboration with Dr. Claudia Rauter (University of Nebraska-Omaha), we are broadening the study of JH to include JH effects on metabolic rates, which are known to vary predictably during the parental cycle.

Microbiology of carcass preparation

Gram stain of anal secretion

Paula Philbrick

Burying beetles are thought to control the decomposition of a small carcass by burying, removing hair or feathers, rounding, and applying antimicrobial anal and oral secretions. These secretions, however, are loaded with their own particular microbial community that will proliferate once on the carcass. Working with Dr. Paula Philbrick (UConn-Waterbury) we are investigating whether burying beetles are manipulating the microbial community to their advantage rather than simply disinfecting the carcass.

Parental care

Biparental care

Biparental care is increasingly viewed as a conflict. On the other hand, there is much attention to how cooperation can evolve among individuals in groups, particularly in the social insects. I feel that it will be instructive to view these two situations from a common perspective: biparental care as a potentially cooperative effort of two unrelated individuals in which both individuals benefit from greater group productivity (more offspring) while attempting to minimize costs by manipulating the partner to provide more care. As in social insects, specialization may promote stable groups because a deserted individual will not be able to perform nonspecialist tasks as efficiently as its partner.

Nicrophorus pustulatus as a parasitoid of snakes

N. pustulatus male releasing pheromone from a snake egg

Derek Sikes collecting Nicrophorus on a badger carcass in China

N. pustulatus has been an enigmatic species of burying beetle because it was never found breeding on a small carcass. Drs. Gabriel Blouin-Demers and Patrick Weatherhead (University of Illinois-Urbana) found N. pustulatus adults and larvae in the nests of the black rat snake (Elaphe obsoleta). Working in our lab, Garrison Smith (M.S., University of Arizona) determined that this species is well adapted to exploiting reptile eggs using many of the same behaviors that congeners use when exploiting carcasses (see September, 2009 issue of Natural History). The closest phylogenetic relatives of N. pustulatus (determined by Derek Sikes, University of Alaska-Fairbanks Museum) have not been studied so it is unknown whether additional nicrophorine species act as parasitoids of reptiles.

Publications

Reviews

Trumbo, S.T. 2013. Maternal care, iteroparity and the evolution of social behavior: a critique of the semelparity hypothesis. Evolutionary Biology 40:613-626. DOI: 10.1007/s11692-013-9237-4.